Problem: A circle with area $4\pi$ has a sector with a $300^\circ$ central angle. What is the area of the sector? ${4\pi}$ $\color{#9D38BD}{300^\circ}$ ${\dfrac{10}{3}\pi}$
The ratio between the sector's central angle $\theta$ and $360^\circ$ is equal to the ratio between the sector's area, $A_s$ , and the whole circle's area, $A_c$ $\dfrac{\theta}{360^\circ} = \dfrac{A_s}{A_c}$ $\dfrac{300^\circ}{360^\circ} = \dfrac{A_s}{4\pi}$ $\dfrac{5}{6} = \dfrac{A_s}{4\pi}$ $\dfrac{5}{6} \times 4\pi = A_s$ $\dfrac{10}{3}\pi = A_s$